Immoral
by lifedistilled
Summary: Severus and Cassie have nothing in common. Cassie is a seventh year Ravenclaw. He is her Potions Master. The only similarity they bear is their mutual attraction to each other. But is it purely physical, or something more? And if it is love between a student and her teacher, isn't it destined for failure?
1. Chapter 1

Warning: this story contains a mature, student/teacher relationship. If this offends you, I suggest you find another story.

Severus sat behind his desk and tried to mark the stack of essays written on parchment in front of him, but all he could think about was the fact that he was definitely, _definitely_ a terrible man. In front of him sat his seventh year Potions class and front and centre was the bane of his existence, Cassandra Poise. Bane of his existence...star of his fantasies. It was the same difference.

As his eyes wandered to the object of his thoughts, Severus silently cursed himself and resumed marking the essays. There was a special cell in Azkaban reserved for people like him he was sure. And he would certainly run the risk of ending up there if he were ever to intimately engage with one of his students. He wasn't in denial about that. He was simply completely attracted to his student. He wouldn't even give himself the excuse that Cassie looked considerably older than she actually was. A lot of seventh years already looked like adults, but that didn't give Severus the excuse to ogle them. Not that he'd ever been so inclined before. He'd never once been attracted to a student before Cassie hit her sixth year at Hogwarts.

The moment Cassie had walked into his room at the start of that year, a jolt of arousal had shot straight through Severus. He hadn't been able to stand up and start the class for a further five minutes afterwards, ever since that moment, he'd been trying to figure out why he was so attracted to Cassie. Yet still he didn't have an answer. Cassie was, obviously beautiful. Some would say extremely attractive. Thick, curly brown hair, brown eyes the colour of milk chocolate, definite cheek bones paired with a smooth heart-shaped jaw, narrow shoulders and curvy hips. Not to mention full breasts. Her school blouses strained over her ample bosom. Even though a lot of Severus' students were beautiful, but he noticed that in a clinical way - in the same way that, as a straight man, he acknowledged that some men were better looking than others. He could see it, but he was entirely unaffected. That's how it had always been with his students; he knew that he was old enough to be parents to most of them. But when Cassie Poise entered he was having dreams during which she ended up bent over his desk.

He couldn't act on the attraction, ever, of course, but no matter how hard he'd tried, he couldn't make it go _away_ either. It was getting harder and harder to keep himself focused on anything but Cassie when third lesson rolled around. Every day, he just prayed for the end of the year. Then he would never have to see Cassie Poise again.

Strangely, he felt a moment of sadness at the thought.

/

Cassie pretended to read the section they were supposed to be covering while surreptitiously watching Professor Snape watching him. None of her friends around her knew it, but he was the subject of her obsession. Her Potions lessons consisted of her own personal fantasies in which he would ask her to stay after class and proceed to ravish her. Her fantasies normally involved Professor Snape's desk. Personally, Cassie would love to be on top of him as he sat on it.

Honestly, what was not hot about him? He had black hair that was quite long but not too much and still he didn't have a fleck of grey. Cassie though his dark hair was one of the sexiest things about him. There were little lines at the corners of his ebony eyes and creases around his mouth. Cassie thought that was sexy too. Really, she thought all of Professor Snape was sexy - certainly his body, which got shown off very nicely when he removed his outer robes. She didn't know how old her professor was, but she did know that Severus Snape was a man who was ageing _well_.

She also knew that he was attracted to her too.

Cassie hadn't thought so at first. She'd been completely attracted to Professor Snape from the start of Hogwarts, but her professor had treated her as he did everyone else, so she'd tried to ignore the feeling. Then, only two weeks ago, she'd seen Professor Snape checking out her arse as she left class. Sure, Cassie had only caught his reflection in the window of the classroom door, but there was no mistaking the look in his eye. After that, Cassie had started to pay more attention. She'd found that Professor Snape's eyes seemed to go to her whenever he thought she wasn't looking. Once, when Professor Snape had stood up to admit someone into the room, she'd sworn there was a slight bulge in his trousers. Yes. Her professor was every bit as into her as she was into him.

It was strange. Cassie had never thought of sleeping with a teacher before. She'd heard rumours of students from Muggle schools who had done so and had always kind of figured they were...well, sluts - or trying to get a better grade. But Cassie wasn't concerned with getting a better grade, and she wasn't slutty either. She'd only had sex with one guy in sixth year and she hadn't so much as had a boyfriend since then, much less had sex. She was just really, _really _attracted to Professor Snape.

She should probably have some kind of problem with sleeping with him, such as the fact that their current relationship was teacher/student. She really...didn't, though. He wanted Professor Snape. Professor Snape wanted her. Cassie was eighteen, so if they had sex, they were two consenting adults. Aside from the student/teacher thing, there was no reason they shouldn't have sex. Okay, sure, it's not like having sex with a teacher was a small thing, but it was something she was totally on board with at this point. It wasn't that weird. She was already spending her third lesson picturing herself and Professor Snape doing unspeakable things to each other. She might as well actually do them. If things got weird, well, there was only two months until the end of the year. She could tough it out - it couldn't be worse than her last and only breakup.

So, she'd do it. She would definitely do it. She would seduce Professor Snape.

/

Author's Note: I realize that this chapter just makes the story look like PWP (even though some of you may like that!) but rest assured, there will be some plot - as well as lemons obviously. A perfect mix of both, you might say. Please leave a review! The more reviews I get the more motivated I will be to update. And it's about to get smutty.


	2. Chapter 2

Thank you to the people who favourited and followed this story! You inspired me to do this chapter quickly.

/

Cassie began her seduction the next day, with a short skirt. Though it wasn't really her style, it was tight fitted and only came to mid thigh. She paired the black mini skirt with a crisp white shirt that was a little too tight over her shoulders, stomach, and breasts. Normally, Cassie couldn't honestly care less about what she put on. She barely checked to see if her clothes were ironed when she put them on. The thought she put into this look was entirely for Professor Snape's benefit.

Her effort was rewarded. While Professor Snape was stood in the doorway to his classroom, Cassie walked in. She could _feel_ Professor Snape's eyes on her arse. Cassie turned and met his eyes, making Professor Snape start to turn away, but not before Cassie could clearly read the hunger in his endless black eyes. Cassie would call that a victory or at least a very good start.

Step two: make the classroom freezing. She walked to the corner of the classroom and cast a small chilling jinx, not that it was particularly warm in the dungeons to begin with. By the time the whole class had come into the room and Professor Snape was at his desk ready to begin the lesson, it was extremely cold and several people around her were shivering. And Cassie's nipples were hard and showing through her thin blouse, as planned. Cassie took her textbook out and started to read it, then flicked a glance at Professor Snape. The skin of his neck had taken on a touch of pink as he looked at Cassie. To hide her grin and continue with her seduction, Cassie leant back in her chair and stretched, making her too-small shirt ride up her stomach, baring a quick (but not too quick) flash of tanned skin. Was that sweat on Professor Snape's upper lip? This was going so well.

The entire lesson period progressed like that. Cassie did nothing overt, nothing that would clue her classmates in about what she was up to, but a dozen tiny seductions spread out over the sixty minute lesson. Since Professor Snape was incapable of standing when the lesson ended (probably because Cassie's flirting had resulted in a potentially embarrassing bulge in his trousers), Cassie took her time getting her things together and made sure she was the last to leave the room. When she finally walked past Professor Snape's desk, she dropped a note on it - her last act of seduction for the day.

/

Severus watched Cassie leave, torn between anger and blistering, aching need. He didn't know what he'd done to reveal his attraction to his student, but Cassie obviously knew and was either on board with the idea or just teasing him because she had that power now. All throughout the lesson, he'd been in an agony of lust as Cassie did one thing or another to bare skin or show off her curves - or her arse; Merlin, that fucking skirt. He found it hard to believe the thing hadn't been a belt. He'd been sure that he was going to go up in a ball of flames when he got a look at Cassie's arse in that thing and all he'd been able to think about was ripping it off. It was as much a sin as his attraction to Cassie was.

At the thought of Cassie in that skirt, his already very existent erection throbbed heatedly. He groaned quietly and shifted in his seat. Then he thanked Merlin that he didn't have a lesson to teach next, because it didn't look like it was going to go away any time soon.

This was such a mess - him, lusting after one of his students. Cassie was either teasing him for fun or... because she was attracted to him as well. The latter was not something that Severus wanted to even casually consider. For one thing, it was highly unlikely. Since she'd started Hogwarts, Cassie had gotten attention from several male students. Although she didn't seem the slightest bit aware. The sinful side of Severus, (the brain located in his trousers), pointed out that Cassie never seemed to be interested in schoolboys. Severus pushed that thought aside. Besides that, Cassie was an eighteen-year-old girl. Severus was forty-two-years-old. What kind of teenager Cassie's age would be attracted to a man that was his age? It just wasn't likely - even if Cassie _was _actually attracted to Severus (which he found to be unbelievable), that wouldn't make anything between them tolerable. Severus was the professor. Cassie was the student. Something between them would just be unacceptable.

_Not if nobody knows_, the sinful Severus pointed out. He stifled a groan and braced his forehead on his hand. No, even if it could be kept quiet, it would still be wrong – ethically and morally. And that's assuming that it could be kept secret. Things of this nature always seemed to get out and if it did, Severus could lose his job. Severus -

He cut himself off right there. He was not going to think about the consequences like actually having an affair with Cassie was a possibility. He didn't need to consider what might happen if he and Cassie got caught because there was never going to be anything to catch. He had been a professor for nearly twenty years; he had never before violated his principles like this.

_I've never been tempted like this before, either_, a small part of his brain whispered to him. He tried to shut that down, too, but couldn't refute it. He _had_ never been this tempted before in his life. That still didn't allow him to give in. And he wouldn't. Of course he wouldn't.

His gaze fell on the note that Cassie had dropped onto his desk. He'd almost forgotten about it, he'd been so caught up in his thoughts. He picked it up. Really, he should just throw it away. Nothing good could come from reading it. Yet as he started to throw it away, he stopped and unfolded the paper, almost without conscious thought. Written in Cassie's italic, neat handwriting was:

_In case you were wondering, no, I wasn't wearing underwear under that skirt._

Severus groaned allowed and dropped the note - Merlin. He was in deep.

/

Not really any lemons in this chapter, but I don't want Cassie to come across as _too much_ of a slut. I hope nobody's put off by the sexual nature of the attraction (but really, I couldn't see Snape feeling love for one of his students from across the classroom). There's more to come between them. (;

Please review, whether you like it or not. It makes me update faster!


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